The present invention relates to intraparenchymal drug infusion, for example by means of convection enhanced delivery (CED). More particularly, it relates to systems and methods for evaluating infusate delivery effectiveness as part of an intraparenchymal drug infusion procedure.
Intraparenchymal (IPA) drug infusion is useful in effectuating a variety of medical treatments at a target tissue site of various anatomical areas. For example, intracerebral IPA drug infusion is a common technique for delivering drugs to selected portions of a patient's brain, relying upon convection to directly infuse brain tissue with therapeutic drugs thereby bypassing the blood-brain barrier. In general terms, IPA drug infusion can be performed on an acute or chronic basis, and typically entails an exit port of a delivery tube (e.g., catheter) being positioned at the tissue target site. The drug (e.g., pharmaceutically active agent that can include biologic materials such as protein(s), virus(es), RNA strands, etc.) is provided in a liquid format (e.g., mixed with saline) and is forced through the delivery tube and thus to the target site, for example via an infusion pump that can be located external the patient or implanted (along with the delivery tube) within the patient.
Effective IPA drug therapy requires successful delivery of the drug. A selected drug likely cannot provide desired therapeutic results without reaching, and subsequently being generally retained at, the intended target site or region. For many IPA drug infusion procedures, it is exceedingly difficult to determine whether or not the drug was successfully or accurately delivered, due to the highly confined nature of the organ/parenchymal tissue in question (e.g., a neurosurgeon cannot readily visualize the brain parenchyma/infusate interface in connection with an intracerebral IPA drug infusion procedure as the exit port of the delivery tube is buried within the brain). Under these circumstances, an available technique for confirming delivery effectiveness is to include a surrogate tracer in the infusate and monitor the volume of distribution in real-time using intraoperative imaging (e.g., MRI). Unfortunately, FDA-approved surrogate tracers are not available for many therapeutic agents. Further, operating rooms typically do not include an MRI system (or similar imaging system). As a result, conventional IPA drug infusion procedures do not afford the neurosurgeon with images of the delivered infused media, such that for many IPA procedures, the neurosurgeon has no positive feedback regarding infusate delivery effectiveness, and thus cannot evaluate whether targeted tissue was infused and/or that it was infused to a desired extent.
In light of the above, a need exists for IPA drug infusion systems and methods that provide feedback to the neurosurgeon or other user from which an evaluation as to infusate delivery effectiveness of the infusion procedure can be performed.